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  • Author or Editor: R. Fouchard x
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Abstract  

KDNBF (potassium 4,6-dinitrobenzofuroxan) has been used as a primer explosive in igniters and detonators for many years. Considerable information about the sensitivity of KDNBF to various stimuli, such as impact, friction, shock and electrostatic charge, is known. However, the thermal sensitivity of KDNBF has been relatively unexplored. Hence, there is very little information available concerning the fundamental thermal properties of KDNBF. Therefore, as part of an extensive thermal hazard assessment, DSC, TG, accelerating rate calorimetry (ARC) and heat flux calorimetry (HFC) measurements have been undertaken on KDNBF. The results demonstrate that KDNBF decomposes via a multi-step exothermic process directly from the solid state. The decomposition process does not appear to depend on the nature of the atmosphere, except in the final stage of the TG decomposition in air, where remaining carbonaceous material is converted to CO2. The first stage of the decomposition is sufficiently rapid that ignition occurs if too large a sample is used. Dynamic and isothermal methods were used to obtain the kinetic parameters and a range of activation energies were obtained, depending on the experimental conditions. The kinetic results have been analyzed in terms of various solid state decomposition models.

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Abstract  

Isopropylnitrate (IPN) is described as a detonable material used in propellants and explosives. While there is considerable information available on its sensitivity and compatibility with other materials, very little is known about its thermochemical properties. This paper will describe the results obtained from some DSC, heat flux calorimetry (HFC) and accelerating rate calorimetry (ARC) measurements. The ASTM DSC method using a hermetic aluminum pan having a lid with a laser-produced pin hole was used to determine the vapour pressure of IPN1. Results calculated from an Antoine equation are in substantial agreement with those determined from DSC measurements. From the latter measurements, the enthalpy of vaporization was determined to be 35.320.62 kJ mol−1. Attempts to determine vapour pressures above about 0.8 MPa resulted in significant decomposition of IPNg. The enthalpy change for decomposition in sealed glass systems was found to be -3.430.09 kJ g−1 and -3.850.03 kJ g−1, respectively from DSC and HFC measurements on IPN1 samples loaded in air. Slightly larger exotherms were observed for the HFC results in air than those in inert gas, suggesting some oxidation occurs. In contrast, no significant difference in the observed onset temperature of about 150C was observed for both the HFC and ARC results. From DSC measurements, an Arrhenius activation energy for decomposition of 1264 kJ mol−1 was found. These measurements were also conducted in sealed glass systems and decomposition appeared to proceed primarily from the liquid phase.

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Abstract  

While there is abundant literature describing the factors affecting the performance and the mechanical sensitivity of black powder, only a few papers are devoted to its thermal properties. Previous work indicated that no exothermic reactions were observed below 300C in an inert gas environment. In the present work a variety of thermal techniques (DSC, TG, simultaneous TG-DTA-FTIR-MS, ARC, HFC) has been used to study the thermal decomposition of black powder. Exothermic reactions were observed at temperatures as low as 230 and 140C in inert and oxidizing atmospheres, respectively. The latter exothermic reaction is due to sulfur oxidation.

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Abstract  

The thermal properties of Alex, a nanosized Al powder, were determined using various techniques, including DSC, TG, simultaneous TG-DTA (SDT) and accelerating rate calorimetry (ARC). The results demonstrate that the specific heat capacities of nano and micron size Al powders are similar between 30 and 400C. Dynamic and isothermal methods were used to determine the kinetic parameters for the oxidation reaction of Alex, which was detected at an onset temperature of 481C. The results obtained were in good agreement with each other. From the ARC experiments, exotherms were detected near 340 and 260C for experiments started at ambient pressure and at 0.72 MPa, respectively.

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